Nakazawa, R.; Nagami, S.; Nozaki, H.; Yataka, M.; Akiyama, K.; Uchino, T.; Azuma, N.
Published in: Medical Gas Research, Volume 15, Issue 1 (2025)
[DOI: pending]

Background

Fatigue is a pervasive and debilitating symptom among patients undergoing hemodialysis (HD) and is associated with increased mortality, cardiovascular risks, and depression. Its multifactorial etiology includes anemia, fluid/electrolyte imbalance, and the physiological stress induced by the dialysis process. Previous studies suggest that hydrogen gas (H₂) possesses both antioxidant and anti-inflammatory properties that could be beneficial in this setting.

Objective

To explore the therapeutic potential of combining hydrogen gas inhalation and hydrogen-enriched dialysate in improving fatigue and health-related quality of life in HD patients.

Methods

Two HD patients received 2.5% hydrogen gas inhalation via nasal cannula connected to a H₂ generator (H2JI1, Doctors Man Co., Japan) at a rate of 250 ml/min, 3 times per week for 4–5 hours during dialysis sessions.
The intervention lasted 3 months and was conducted alongside electrolyzed water online hemodiafiltration (EW-OL-HDF).

Parameters measured:

• Fatigue: SONG-HD (0–9 scale)

• Perceived health: EQ-VAS (0–100 scale)

• Biomarkers: Serum levels of citrullinated histone H3 (CitH3), non-mercaptalbumin, advanced glycation end products (AGEs), and flow-mediated dilation (FMD).

• Hydrogen levels in dialysate and blood were monitored by dissolved H₂ meter and gas chromatography respectively.

Results

• Fatigue scores (SONG-HD) improved dramatically:

  • From 9 (conventional HDF) → 3 (EW-OL-HDF) → 0 (combined therapy) for both patients.

• EQ-VAS scores improved:

  • From 0 (conventional HDF) → 30/35 (EW-OL-HDF) → 100 (combined therapy).

• Upon return to conventional HDF, both fatigue and EQ-VAS scores reversed (fatigue = 9, EQ-VAS = 0).

• Biomarker improvements included:

  • Decrease in CitH3, oxidative stress, and inflammatory markers.

  • Improvement in vascular function (FMD).

Conclusion

These two case studies suggest that the dual intervention of hydrogen gas inhalation combined with hydrogen-enriched dialysate may offer remarkable relief from fatigue in HD patients, potentially via reduction of oxidative stress and inflammation.
Although based on a small sample, the findings provide a strong rationale for further investigation in larger, controlled cohorts considering age, gender, and biomolecular markers over extended periods.

Dong, G.X.; Wu, J.X.; Hong, Y.L.; Li, Q.; Liu, M.; Jiang, G.L.; Bao, D.P.; Manor, B.; Zhou, J.H.
Published in: International Journal of Sports Medicine, Vol. 45, Issue 13 (2024)
[DOI: pending]

Background

Hydrogen gas (H₂), recognized for its antioxidant properties, has shown potential to mitigate exercise-induced oxidative stress and fatigue. This study investigates the acute ergogenic effects of hydrogen-rich gas (HRG) inhalation prior to strenuous physical activity — a previously unexplored approach.

Objective

To determine whether pre-exercise inhalation of hydrogen-rich gas improves fatigue resistance, subjective exertion, and biochemical markers during high-intensity cycling exercise.

Methods

• Study design: Double-blind, randomized, placebo-controlled crossover trial

• Participants: 24 healthy adult males

• Protocol:

  • Baseline testing of maximal cycling power (Wₘₐₓ) and time to exhaustion (Tₘₐₓ)

  • Subjects then completed an exhaustive cycling protocol at 80% Wₘₐₓ after 60-minute inhalation of either:

    • Hydrogen-rich gas (HRG)

    • Placebo gas (ambient air)

• Evaluated variables:

  • Fatigue perception via Visual Analog Scale (VAS)

  • Rating of Perceived Exertion (RPE)

  • Cycling cadence during last 30s of fatigue model

  • Jump performance (Countermovement Jump, CMJ)

  • Biomarkers: Serum lactate, hydroxyl radical scavenging activity, glutathione peroxidase (GPx)

Key Results

• Significant improvements were observed with HRG vs. placebo in:

  • VAS fatigue scores

  • RPE

  • Cycling cadence during final effort phase

  • Post-exercise serum lactate reduction

  • Hydroxyl radical neutralization capacity

• No significant effect on:

  • CMJ height

  • GPx activity

p-values for significant effects: p < 0.028

Conclusion

Pre-exercise inhalation of hydrogen-rich gas can alleviate subjective and physiological markers of fatigue, sustain motor performance, and enhance antioxidant responses (specifically hydroxyl radical scavenging). These findings point to HRG as a promising acute ergogenic aid in sport and exercise settings.

Lin, F.; Li, R.T.; Chen, Y.; Yang, J.; Wang, K.; Jia, Y.T.; Han, H.Z.; Hao, Q.; Shi, G.Z.; Wang, S.; Zhao, Y.L.; Chen, X.L.

Published in: Trials, Vol. 25, Issue 1 (2024)
[DOI: pending]

Research Background

Aneurysmal subarachnoid hemorrhage (aSAH) is an extremely severe cerebrovascular event with high mortality and neurological morbidity. The main causes of deterioration in patient condition are:

• Delayed cerebral ischemia (DCI)

• Cerebral vasospasm (CVS)

Both complications result from early brain injury (EBI), for which current pharmacological treatment remains limited (primarily oral nimodipine).

Study Objective

The HOMA study (Hydrogen-Oxygen Mixture Administration) aims to:

• Evaluate the efficacy and safety of inhalation therapy using a gas mixture of 67% hydrogen and 33% oxygen

• Determine whether this therapy reduces the incidence of DCI and CVS

• Improve overall outcomes for patients with acute aSAH

Methodology

• Study Type: Open-label, randomized, controlled, single-center clinical trial

• Number of patients: 206

Randomization:

• Intervention group: Inhalation of H₂/O₂ mixture (8 hours daily, 3 L/min)

• Control group: Oxygen only (33%, identical conditions)

• Treatment initiation: Within 72 hours after aSAH

• Treatment duration: 7 days in the ICU

Primary Endpoints:

• Incidence of DCI and CVS during hospitalization

Significance and Potential Benefits

• First large-scale RCT of hydrogen therapy in aSAH patients

• Potential to offer a new, non-invasive neuroprotective treatment

• If efficacy is confirmed, hydrogen inhalation could be integrated into clinical guidelines for acute neurological conditions

• Particularly relevant in regions with rising stroke incidence (e.g., China)

Ethical Considerations

• Study approved by the Ethics Committee of Tiantan Hospital, Capital Medical University (Beijing)

• All findings will be published in peer-reviewed journals and presented at international conferences

Chitapanarux, I. et al.
OncoTargets and Therapy, Volume 17 (2024): 863–870

Clinical Background

Radiotherapy combined with chemotherapy (CCRT) for locally advanced head and neck cancer (LAHNC) is often limited by acute toxicity caused by oxidative stress and inflammatory responses. Hydrogen gas, known for its antioxidant and anti-inflammatory properties, may offer a protective effect by reducing reactive oxygen species (ROS) generated during radiotherapy.

Study Objective

• To evaluate the feasibility and safety of daily hydrogen gas inhalation in combination with standard CCRT.

• Secondary goal: monitor potential adverse events and impact on typical acute treatment toxicities.

Methods

• Design: Prospective pilot study (n = 10)

• Hydrogen Inhalation: 1 hour per day, 1–2 hours before radiotherapy (IMRT), via cannula or mask

• Radiotherapy: 33 fractions (weekdays)

• Chemotherapy: 6 weekly cycles

• Study Period: July to December 2023

Primary Endpoint:

• ≥80% of patients must complete at least 20 inhalations → criterion for feasibility.

Secondary Endpoints:

• Vital signs and safety (blood pressure, symptoms)

• Incidence of acute toxicity during CCRT

Results

• 100% of patients completed 33 inhalations (100% adherence)

• Safety: No hypertension, hypotension, or symptoms such as coughing, epistaxis, dizziness, headache, nausea, or vomiting

• Treatment-related toxicities:

  • Grade 3 leukopenia in 2 patients (20%) during week 5

  • Grade 2 radiation dermatitis and pharyngitis in 3 patients (30%)

All observed toxicities were attributed to CCRT and not to hydrogen gas inhalation.

Conclusion

• Hydrogen gas inhalation is feasible and well-tolerated in patients with LAHNC.

• No acute side effects directly related to hydrogen inhalation were observed.

• The study supports the safety profile for future larger randomized controlled trials to evaluate efficacy in preventing radiation complications and reducing toxicity.

Rahman, M.H.; Bajgai, J.; Sharma, S.; Jeong, E.S.; Goh, S.H.; Jang, Y.G.; Kim, C.S.; Lee, K.J.

Published in: Antioxidants, Volume 12, Issue 6 (2023)
DOI: 10.3390/antiox12061241

Research Background

Molecular hydrogen (H₂) is a versatile therapeutic agent. Inhalation of hydrogen gas has been reported to be safe and beneficial for a variety of conditions, including Alzheimer’s disease (AD).

Study Objective

The aim of this study was to investigate the effects of a 4-week hydrogen gas inhalation regimen on community-dwelling adults of various ages.

Methodology

• Study design: Single-arm, open-label, prospective clinical trial

• Participants: 54 individuals enrolled, including a 5% dropout rate

• Approach: All participants were treated as one group, without randomization

• Main evaluations:

  • Changes in total and differential white blood cell (WBC) counts

  • Changes in Alzheimer’s disease-related biomarkers after 4 weeks of H₂ gas inhalation

Results

• Safety and Tolerability: Total and differential WBC counts remained unaffected, indicating that hydrogen gas inhalation was safe and well tolerated.

• Oxidative Stress: Levels of reactive oxygen species (ROS) and nitric oxide (NO) significantly decreased following treatment.

• Cognitive and Biomarker Improvements: Notable improvements were observed in biomarkers associated with dementia and cognitive function, including:

  • BACE-1 (β-site APP cleaving enzyme 1)

  • Amyloid beta (Aβ)

  • Brain-derived neurotrophic factor (BDNF)

  • Vascular endothelial growth factor A (VEGF-A)

  • Total Tau (T-tau)

  • Monocyte chemoattractant protein-1 (MCP-1)

  • Inflammatory cytokine IL-6

Most participants showed a significant improvement in cognitive status post-treatment.

Conclusion

The findings suggest that hydrogen gas inhalation may be a promising intervention for improving cognitive dysfunction and potentially mitigating symptoms associated with Alzheimer’s disease in community-dwelling adults of various ages.

Chen, J.B.; Mu, F.; Lu, T.Y.; Du, D.M.; Xu, K.C.

Published in: OncoTargets and Therapy, Volume 12 (2019)
DOI: 10.2147/OTT.S210055

Research Background

Lung cancer is the most common type of cancer prone to contralateral metastases, especially to the lungs, bones, and brain. Treatment of brain metastases in non-small cell lung cancer (NSCLC) remains challenging, particularly after failure of standard therapies.

Methodology & Case Overview

• Patient: 44-year-old woman diagnosed with NSCLC and multiple metastases

• Initial treatment: Brain metastases surgically removed; oral targeted therapy followed

• Course:

  • Over 28 months, the majority of lesions remained stable

  • In March 2018, new intracranial multiple metastases and hydrocephalus (third and lateral ventricles) were discovered, alongside new metastases in bone, adrenal glands, and liver

• Intervention:

  • April 2018: Initiation of hydrogen gas monotherapy for tumor control

  • After 4 months:

    • Marked reduction in brain tumor size

    • Significant decrease in ventricular hydrocephalus

  • After 1 year:

    • Complete disappearance of brain tumors

    • No notable change in liver or lung metastases

Conclusion

This case suggests that hydrogen gas monotherapy, initiated after failure of standard treatments, may result in effective tumor control, especially in the brain, and contribute to prolonged survival in patients with advanced NSCLC.

Khaliq, U.; Zaka, S.; Tariq, H.

Published in: Indo American Journal of Pharmaceutical Sciences, Volume 5, Issue 11 (2018)
DOI: [Unavailable]

Background

Asthma is a chronic inflammatory disease of the airways involving numerous immune cells and cellular elements. Chronic inflammation leads to recurring episodes of wheezing, breathlessness, chest tightness, and coughing, especially at night or early in the morning.

Study Objective

The primary goal of the study was to measure the levels of antioxidants as a result of hydrogen gas inhalation, assessing its potential to reduce oxidative stress in asthmatic patients.

Methodology

• Location: Conducted in hospitals in Mandi Bahauddin in collaboration with Services Hospital, Lahore

• Year: 2018

• Participants: Male and female asthmatic patients

• Procedure: Blood samples were taken from all participants to analyze antioxidant levels before and after hydrogen gas inhalation

Results

• The study measured average values before and after hydrogen gas inhalation, expressed as mean ± SD

• Antioxidant levels showed:

  • Increase in SOD (superoxide dismutase)

  • Increase in MDA (malondialdehyde)

  • Increase in GSH (glutathione)

  • Decrease in catalase levels, reaching 0.43 ± 0.39

These findings suggest a disruption in the antioxidant balance in the bloodstream post-inhalation.

Conclusion

The study concludes that hydrogen gas inhalation may alter the balance of antioxidants in the blood of asthmatic patients. More clinical studies are required to establish the clinical safety and protective effects of hydrogen gas when used at the bedside.

Ono, H.; Nishijima, Y.; Ohta, S.; Sakamoto, M.; Kinone, K.; Horikosi, T.; Tamaki, M.; Takeshita, H.; Futatuki, T.; Ohishi, W.; Ishiguro, T.; Okamoto, S.; Ishii, S.; Takanami, H.

Published in: Journal of Stroke & Cerebrovascular Diseases, Volume 26, Issue 11 (2017)
DOI: [Pending]

Background

Molecular hydrogen (H₂) acts as a therapeutic antioxidant. Inhalation of H₂ gas (1–4%) has shown effectiveness in improving cerebral infarction in several animal studies. Therefore, a randomized controlled clinical trial is required to assess its effects in actual medical application.

Objective

To evaluate the safety and neuroprotective efficacy of H₂ gas inhalation therapy in acute cerebral infarction (stroke) patients.

Methodology

• Design: Randomized Controlled Clinical Trial

• Participants: 50 patients (25 per group) with mild to moderate acute cerebral infarction, NIH Stroke Scale (NIHSS ≤ 26)

• Therapeutic window: 6–24 hours from onset

• Intervention group: Inhaled 3% hydrogen gas, 1 hour twice daily for 7 days

• Control group: Received standard intravenous therapy for 7 days

• Evaluation parameters:

  • Daily vital signs

  • NIHSS scores

  • Physical therapy indices (e.g., Barthel Index)

  • Weekly blood biochemistry

  • Brain MRI scans over the 2-week study period

Results

• No significant adverse effects were observed in the hydrogen group

• Improvement in oxygen saturation was noted

• Statistically significant benefits in:

  • MRI signal intensity, indicating lesion severity

  • NIHSS scores, reflecting stroke severity

  • Barthel Index, measuring physical therapy outcomes

Conclusion

Hydrogen gas therapy was found to be safe and effective in patients with acute cerebral infarction. These findings suggest that H₂ inhalation has broad potential for clinical application in neuroprotection.

Katsumata, Y.; Sano, F.; Abe, T.; Tamura, T.; Fujisawa, T.; Shiraishi, Y.; Kohsaka, S.; Ueda, I.; Homma, K.; Suzuki, M.; Okuda, S.; Maekawa, Y.; Kobayashi, E.; Hori, S.; Sasaki, J.; Fukuda, K.; Sano, M.

Published in: Circulation Journal, Volume 81, Issue 7 (2017)

Background

Hydrogen gas inhalation (HI) has been shown to reduce infarct size and mitigate adverse left ventricular (LV) remodeling in rat models of acute myocardial infarction (AMI). This study aims to translate those findings into the clinical setting.

Objective

To conduct a prospective, open-label, evaluator-blinded pilot clinical study investigating the effects of hydrogen inhalation during primary PCI in patients with ST-elevation myocardial infarction (STEMI).

Methodology

• Participants: 20 patients with an initial diagnosis of STEMI

• Groups:

  • HI group: received 1.3% hydrogen gas with 26% oxygen

  • Control group: received 26% oxygen only

• Primary endpoint: Myocardial salvage index assessed by cardiac MRI at 7 days post-PCI

Results

• No serious adverse events related to hydrogen inhalation occurred

• Myocardial salvage index:

  • HI group: 50.0 ± 24.3%

  • Control group: 60.1 ± 20.1%

  • P = 0.43 (not statistically significant)

• However, at 6-month follow-up, the HI group showed numerically greater improvements in:

  • LV stroke volume index:

    • HI: +9.2 ± 7.1 ml/m²

    • Control: −1.4 ± 7.2 ml/m²

  • LV ejection fraction:

    • HI: +11.0 ± 9.3%

    • Control: +1.7 ± 8.3%

Conclusion

This first human pilot study demonstrated that hydrogen gas inhalation during PCI is feasible and safe, and may promote reverse LV remodeling over a 6-month period after STEMI.
Note: The study was not powered to assess efficacy, and a larger trial is planned.

Sano, M.; Ichihara, G.; Katsumata, Y.; Hiraide, T.; Hirai, A.; Momoi, M.; Tamura, T.; Ohata, S.; Kobayashi, E.
Published in: PLOS ONE, Volume 15, Issue 6 (2020)
https://doi.org/10.1371/journal.pone.0234626

Background

Although the benefits of hydrogen gas (H₂) inhalation have been extensively reported, its pharmacokinetics remain insufficiently characterised.

Objective

To develop a novel experimental pig model for the detailed evaluation of the absorption of H₂ through the lungs, its entry into the bloodstream, systemic distribution, metabolism, and excretion.

Methods

Catheters were surgically inserted into the carotid artery (CA), portal vein (PV), and suprahepatic inferior vena cava (IVC) to enable repeated blood sampling. Bilateral thoracotomy was performed to collapse the lungs, and a hydrogen-absorbing alloy canister was used to inflate the lungs to full inspiration with 100% hydrogen gas. The animals were maintained without respiration for 30 seconds, simulating breath-hold. Blood was collected from the three catheters at 0, 3, 10, 30, and 60 minutes, and hydrogen concentrations were measured via gas chromatography.

Results

• Peak H₂ concentration in CA occurred immediately post-inhalation and dropped to 1/40th of that value within 3 minutes.

• The maximum H₂ concentrations in PV and IVC reached 40% and 14%, respectively, of those in the CA.

• H₂ clearance was slower in PV and IVC (half-lives: 310 and 350 seconds) than in CA (half-life: 92 seconds).

• At 10 minutes, H₂ concentrations were significantly higher in venous than arterial blood.

• At 60 minutes, residual H₂ levels in PV and IVC remained 6.9–53 nL/mL and 14–29 nL/mL above baseline, respectively, while arterial levels returned to baseline.

Conclusion

These findings indicate that inhaled hydrogen gas is transported systemically via advection and diffusion, followed by dynamic metabolism and clearance. The study offers valuable insights into the time-dependent tissue distribution of hydrogen and underlines the potential of H₂ inhalation for clinical applications.

Nascimento, G.C.; Santos, B.M.; Pedrazzi, J.F.; Silva-Amaral, D.; Bortolanza, M.; Harris, G.T.; Del Bel, E.; Branco, L.G.S.
Published in: Brain, Behavior & Immunity – Health, Volume 30 (2023)
https://doi.org/10.1016/j.bbih.2023.100623

Background

L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia is a common adverse effect of Parkinson’s disease therapy, characterised by abnormal involuntary movements (AIMs). There is documented evidence linking neuroinflammation to the onset and severity of L-DOPA-induced dyskinesia. Hydrogen gas (H₂) has shown neuroprotective and anti-inflammatory properties in various Parkinson’s disease models.

Objective

To test the hypothesis that inhalation of hydrogen gas reduces L-DOPA-induced dyskinesia in a preclinical rat model of Parkinson’s disease.

Methods

Rats were subjected to 6-hydroxydopamine lesions (via microinjection into the medial forebrain bundle) to induce dopaminergic neuron degeneration. Fifteen days post-lesion, animals received chronic L-DOPA treatment for 15 days. Prior to each L-DOPA dose, rats were exposed to either:

• 2% H₂ gas mixture for 1 hour, or

• ambient air (control group).

Abnormal involuntary movements (AIMs) and locomotor activity were monitored. Additionally, striatal microglia and astrocytes were analysed, and plasma and striatal samples were collected post-AIMs assessment for cytokine profiling.

Results

• Hydrogen inhalation significantly attenuated L-DOPA-induced dyskinesia, without compromising the locomotor benefits of L-DOPA therapy.

• Striatal microglial activation was reduced in the H₂ group, consistent with lower levels of proinflammatory cytokines.

• AIM severity positively correlated with plasma IL-1β and striatal TNF-α, and negatively correlated with striatal IL-10 (an anti-inflammatory cytokine).

Conclusion

Prophylactic inhalation of hydrogen gas reduces L-DOPA-induced dyskinesia in a preclinical Parkinson’s model. This antidyskinetic effect is associated with a reduction in both central and peripheral inflammation. These findings hold promising translational relevance for improving patient comfort and treatment outcomes in L-DOPA-managed Parkinson’s disease.

Zhang, C.T.; Xing, Y.; Wu, X.F.; Jiang, Q.; Luo, X.Y.; He, W.; Liu, S.Y.; Lu, W.J.; Wang, J.
Published in: Respiratory Research, Volume 25, Issue 1 (2024)
https://doi.org/10.1186/s12931-024-02707-x

Background

Pulmonary veno-occlusive disease (PVOD) is a rare and life-threatening subtype of pulmonary hypertension (PH) for which no effective treatments currently exist. Previous studies have shown that hydrogen gas (H₂) exhibits antioxidative and anti-inflammatory effects in monocrotaline-induced PH rat models.

Objective

To evaluate the preventive and therapeutic effects of hydrogen gas inhalation on mitomycin C (MMC)-induced PVOD in rats.

Methods

Female Sprague-Dawley rats were administered MMC intraperitoneally (3 mg/kg once weekly followed by 1 mg/kg for 2 weeks) to induce PVOD. Hydrogen gas (H₂) was administered via a customized inhalation cage, either concurrently with MMC (preventive model) or starting two weeks post-MMC (therapeutic model).

Assessments included:

• Hemodynamic measurements

• Histological analysis

• Markers of oxidative stress and inflammation

• Key regulatory proteins (GCN2, Nrf2, HO-1, NOX-1)

• Endothelial-to-mesenchymal transition (EndoMT) markers (VE-cadherin, CD31 vs. vimentin, fibronectin)

• Smad signaling phosphorylation status (p-Smad3 and p-Smad1/5/9)

Results

Hydrogen gas inhalation:

• Improved right ventricular function and hemodynamics

• Reduced right ventricular hypertrophy and pulmonary vascular remodeling

• Lowered serum malondialdehyde (MDA) and pulmonary NOX-1 expression

• Activated Nrf2/HO-1 antioxidant pathway and upregulated anti-inflammatory factor GCN2

• Suppressed macrophage infiltration and proinflammatory cytokine production

• Counteracted MMC-induced EndoMT, evidenced by restored endothelial markers and suppressed mesenchymal markers

• Preserved p-Smad3 and induced p-Smad1/5/9, indicating regulatory effects on fibrosis-related pathways

Conclusion

Hydrogen gas inhalation significantly inhibits the pathogenesis of MMC-induced PVOD in rats. These protective effects are attributed to H₂’s antioxidant, anti-inflammatory, and anti-EndoMT activities, making it a promising candidate for the treatment or prevention of PVOD.

Aokage, T.; Iketani, M.; Seya, M.; Meng, Y.; Ageta, K.; Naito, H.; Nakao, A.; Ohsawa, I.
Published in: Experimental Gerontology, Volume 180 (2023)
DOI: 10.1016/j.exger.2023.112270

Background

With the aging global population, the incidence and mortality associated with sepsis and systemic inflammation increase, especially in the elderly. Aging is accompanied by chronic low-grade inflammation and reduced resilience to acute inflammatory insults. Hydrogen gas (H₂) is recognized for its antioxidant and anti-inflammatory properties, but its therapeutic relevance in elderly individuals facing acute inflammatory stress has not been fully clarified.

Objective

To evaluate the therapeutic potential of continuous 2% hydrogen gas inhalation in reducing inflammation-induced pulmonary and hepatic damage, and to assess its impact on aging-related molecular markers and survival outcomes in aged mice exposed to lipopolysaccharide (LPS)-induced systemic inflammation.

Methods

• Subjects: Male mice aged 21–23 months, representative of the geriatric human population.

• Induction of inflammation: LPS administered intraperitoneally.

• Groups: Eight experimental groups with different durations and concentrations of hydrogen gas inhalation:

  • Control (no treatment),

  • Saline ± hydrogen (1% or 2%) for 24 hours,

  • LPS ± hydrogen for 1, 6, or 24 hours at 1% or 2%.

• Endpoints: Survival rate, physical activity, pulmonary and hepatic injury, and molecular markers such as inflammatory cytokines and senescence-associated p21 expression.

Results

• 24-hour continuous 2% hydrogen gas inhalation:

  • Significantly improved survival and physical activity.

  • Reduced mRNA expression of inflammatory cytokines in the lungs and liver.

  • Attenuated lung tissue damage.

  • Decreased expression of p21, a key marker of cellular aging, in lung tissue.

  • Downregulated expression of aging-associated lung markers: CXCL2, MMP-3, and Arg1.

• No significant protection was observed in hepatic tissue despite systemic anti-inflammatory effects.

• Shorter or lower-concentration inhalation protocols (e.g., 1 hour or 1% H₂) showed limited therapeutic benefit.

Conclusion

Prolonged inhalation of 2% hydrogen gas for 24 hours offers substantial protection against LPS-induced pulmonary inflammation and promotes survival in aged mice. It also modulates aging-related markers, suggesting a potential therapeutic role for H₂ inhalation in geriatric patients suffering from acute inflammatory conditions. Further translational studies are warranted to explore its clinical applicability.